← VCE Data Analytics U4O2

Data integrity characteristic: correctness

Data is correct when it is in the right form and follows set rules, such as the right data type, format, valid values and calculation. It is not the same as accuracy.

Part of: VCE Data Analytics - U4O2 - Cyber Security: Data Security — Module 22, ACARA Digital Technologies Years 9–10 — Acquiring and Validating Data — Module 83, QCE Digital Solutions Unit 4 — Complex Digital Data Exchange Problems and Solution Requirements — Module 63

Understanding Data integrity characteristic: correctness in VCE Data Analytics U4O2

What it does: Correctness includes calculations that follow the rules, so the formula must multiply price by quantity to give the right total. A validation rule checks that data follows the rules set for it, such as a mark staying between 0 and 100. Correctness means the data is in the right form. A word in a numeric field is the wrong data type, so it is not correct. Both entries show the same date, but only 14/03/2025 follows the required format, so only it is correct. Valid values are those allowed by the rules set for the field. 15 is outside the range 7 to 12, so it is not correct.

Common mistakes: A whole number is the correct data type for age, so it should be accepted. The ELSE branch is where wrong types are rejected. Line 3 should be ACCEPT age. The rule must set the format the data follows. The value 15/03/2008 is in DD/MM/YYYY form, so the rule should be DD/MM/YYYY.

Class: _____________________  ·  Name: _____________________  ·  Date: _________

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This module's key terms are also in a printable crossword (Modules 1–25) and word search (Modules 1–43).

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Learning
Duo
A student enters 'twenty' into a field that only accepts whole numbers. Which integrity characteristic is this breaking?
Timeliness: the data is out of dateCorrectness: the data is not the right data type
Matches
Phone number field contains: 04AB 123 4X6
↓
The value contains letters, so it is not in the right format for a phone number. This is a correctness error.
Applying
Meanings
Term
Correctness
Meaning
Data is correct when it is in the right form and follows set rules, such as the right data type, format, valid values and calculation. It is not the same as accuracy.
Practice
=IF(AND(ISNUMBER(B2),B2>=0,B2<=100),"Valid","Invalid")
Testing
Gaps
=IF((B2),"Correct type","Wrong type")
Check Answer
Spots
2IF age is a whole number THEN
3 REJECT age

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Quick Questions

1. A student enters 'twenty' into a field that only accepts whole numbers. Which integrity characteristic is this breaking?
A. Timeliness: the data is out of date
B. Correctness: the data is not the right data type ✓
Correctness means the data is in the right form. A word in a numeric field is the wrong data type, so it is not correct.
2. Which statement best describes correct data?
A. It is in the right form and follows the rules set for it ✓
B. It always matches the real-world value exactly
Matching the real-world value describes accuracy. Correctness is about the right data type, format, valid values and calculation.
3. A date field must use DD/MM/YYYY. Which entry is correct?
A. 14/03/2025 ✓
B. March 14th, 2025
Both entries show the same date, but only 14/03/2025 follows the required format, so only it is correct.
4. A rule says student year level must be between 7 and 12. Which value is a valid value?
A. 10 ✓
B. 15
Valid values are those allowed by the rules set for the field. 15 is outside the range 7 to 12, so it is not correct.
5. An invoice total is calculated as price + quantity instead of price x quantity. What is the problem?
A. The data type is wrong, so the data is out of date
B. The calculation is wrong, so the data is not correct ✓
Correct data uses the right calculation. Adding when you should multiply gives an incorrect result, even if the result is a number.

Match the Pairs

Age = "twenty" in a number field → Incorrect data: the value is text, so it is the wrong data type for an Age field
Date of birth entered as 31/02/2005 → Incorrect data: the date breaks the rules because February has no 31st, so it is not a valid value
A correct calculation follows the rule set for it, such as total = price * quantity → Total = Price * Quantity
Valid values must fall within the allowed range set for a field → IF Mark >= 0 AND Mark <= 100 THEN valid
Phone number field contains: 04AB 123 4X6 → The value contains letters, so it is not in the right format for a phone number. This is a correctness error.
A record has the right format but the wrong value, e.g. Maths mark 82 typed when the real mark was 28 → This is an accuracy error, not a correctness error. The mark is valid and in the right form but does not match the real value.

Key Term

Correctness
Data is correct when it is in the right form and follows set rules, such as the right data type, format, valid values and calculation. It is not the same as accuracy.

Fill in the Blanks

1. =IF(ISNUMBER(B2),"Correct type","Wrong type")
Hint: Type the function that checks whether a cell holds a number, which tests the data type.
2. =IF(B2>=0,"Valid","Invalid")
Hint: Type the comparison operator that means greater than or equal to, so a mark can't be negative.
3. =C2*D2
Hint: Type the operator that multiplies price by quantity to give the correct total cost.
4. IF age < 0 OR age > 120 THEN DISPLAY "Invalid age" END IF
Hint: Type the logical keyword that flags the age if either rule is broken.
5. =IF(LEN(A2)=4,"Valid","Invalid")
Hint: Type the function that counts characters, used to check that a postcode follows the required format.

Spot the Error

Question 1
A age ← INPUT()
B IF age is a whole number THEN
C REJECT age
D ELSE
E REJECT age
Line C — A whole number is the correct data type for age, so it should be accepted. The ELSE branch is where wrong types are rejected. Line 3 should be ACCEPT age.
Question 2
A RULE date format = MM-DD-YY
B dob ← '15/03/2008'
C OUTPUT dob
Line A — The rule must set the format the data follows. The value 15/03/2008 is in DD/MM/YYYY form, so the rule should be DD/MM/YYYY.
Question 3
A RULE mark is between 0 and 100
B IF mark >= 0 OR mark <= 100
C ACCEPT mark
Line B — A valid mark must be at least 0 AND at most 100. OR is true for any number, so invalid values like 150 or -5 would pass. It should use AND.
Question 4
A maths ← 80
B english ← 70
C avg ← maths + english / 2
D OUTPUT avg
Line C — Without brackets, division happens before addition, so only english is divided by 2. The calculation is incorrect. It should be (maths + english) / 2.
Question 5
A price ← 50
B qty ← 3
C subtotal ← price * qty
D total ← subtotal + 1.10
E OUTPUT total
Line D — Adding 10% GST means multiplying the subtotal by 1.10. Adding 1.10 gives the wrong calculation. It should be subtotal * 1.10.

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